Application of dispersed materials to cellulosic fibers



Patented June 24, 1952 APPLICATION OF DISPERSEI) LlVIATERIALS T CEISIiULOSIC 1*"IBERS 'John Daniel, 'JrgfStamforiL Lucius H. Wilson, L4Greenwich, Randall Hastings, Stamford, and Chester G. Landes, New Canaan; Co''n'n.,-`as signers to'Ameri'can Cyananlid Company,fNew IYork, N. Y., a' corporation of Maine No'Drawin'g. ApplicationDeceniber-26,1947, l Serial N0. 794,1516

'This inventionl relates :to the application `of f-'eo'ating" or limpregnating materials to fibrous cellulosic material, tocoatedor impregnated celluflosic bers obtainedl thereby, "and `to 'the `manu'- facture'of other articles fromthe coated-ordmapregnated lbers. fMore .'particdlarly, vthe invenition relates 'to the incorporation ofdispersion's i'o' emiilsions-oi" water-insoluble coating for im'- =pregnating-`materialss'ueh as resinsspreeipitated -ioi -fi1fs'ol1ible-sizes,elastomers, waxes, pitches, hitdmens,Soils,-etc., into -brous cellulosic matel suehfa's paper stock', cotton-'and Ithe like, followe'd' if desired by forming the resulting. pretreated eellulosio V1inmaterial into brous felted 1`sneets or lvarticles fsuch as paper, .paper board, llifldedor prein'olded leellu'l'os'fic l articles andthe ilike.l The invention includes l'pro'cesses ffor fthe 'v'maniifacture of `new types' of lpaper, ,paper-fv board,

Apulp and pulp preforrns as well asia 'wide variety Jif rio-vol -produois obiainodfmerefrom, either di- "eetlyforbyeiibseou'enttreatinents'suoh as shedidihg, impregnating 'cold pressingrfhot pressing, f'hefatin'g, .cal'entlering, fhot c'alendering and the vlike.

)Heretofore the principabmethods of incorporating resins, waxes, "waterproong andfgre'ase- "prooiingv agentsbinding agents! and th'ellikev into "a: sheet'of pulp"orpaperhavebeenby impregna- "tion ofthe Yfortifiedl sheetor -objeot -bya -water so1ution,=organio solvent solution or dispersion :of the'lmaterial to be incorporated or by addition" of "the impregnating agent to the pulp-Waterslurry, "calledslushlstook or paper stock,veitlier`as a sub'- stantially water-insoluble drylpo'wderedmaterial orl as-a-'preeipita'teffrom a water so1iition,so1vent 'solution,forfdiSpe-rsionor'emu1sioniof`tho-irnpreg- ,"Ilatingfmaterial. Thus, for vexample, itfis loom'- 'mnpracticetoadd llers such aSola-y Sandi-sizing jrliaterials'such as irosin soap, -rosinf or waxi emu'lsions 4'or' di'spersionsr latices, asphalt :emulsions '40 ahdthe'like Coslush-stoc'k in-thefbeater, stock chest or at any therpointlinthe s'tocksystem prior to sheet formationfpreceded or followed by the addition of alum. BytliisV procedure the siz- -ingimaterials are precipitated and lthe,resul-ting Slides l*are'entangledfor mixedl with. the fibrous paper stock and are carried sinto the nished :papel: u y

Thisv procedure works `fairly Wellin those cases -whereonlyfsmall amounts of certain-materials are'faddedto the paper, suchas amounts on the `"order of Ofi-5% on the Weightof'the ber. vHov'vever,serious-*operating diiiiculties are frequently --encountered whenattempts are made to incorporate larger-quantities o'f impregnating"agents .-bythesemethods. 'Sonie-cr all ofthe following .diiculties-are frequentlyencountered. A i

IThe'resinous material uis agglomerated l in fballs-'onlumps instead of-forining flocs oflsrnall particle size. This may cause the sheet to stick handled j sheets, boards :and preforms con to the presses, l driers, felt's i and 4rcalendfers when the 1 improgna-ted pulp is runout i on: a papernlak?.

in'gmachine.

coverage -of the individu-a1 obers may ibo ipoor.

3. V.Distribution of -the resin in-thesheetmay -Ybe v'non-uniform, yresulting in g a'fmottled appear? ance of the sheet and causing'-nonuniformiink reception. l

4. Sheet formation'is, 'oftenliarrned v5. Water drainage often `ltsecomes'lfoo slow l.for sheet formation u 6. "Precipitation-of the vresin is `frequently incomplete;andmuchfof' theresinous impregna-tuig =material1isilostvinthe-'whitewater'. i

7. 'Agglomerates of lthe Vresin, 'together fwith iunprecipitated resin, 'tend to ydepositl a-s-Istieky aggregates in pipe 1ines,f tanks;andyariouslother portions A of -the papermaking i equipment.

VSome of ithese f diioulties, `v`such `fas theff appearance fof resin-Esprits and. lumps f of agglomerated `r'nat'erial are .frequently encountered :in ','paper 'mills even-'fwhenlamounts'as'sm'all'as 0:25;3.:%2of `certain 'ltypes of .'rosi'n and l"w'axfernulsicm's 'are added;

The present invention fhas.asia :principal fobv:jee't anf-improvedf-metliod for the incorporation -o'f` impregnating agents 'fibrous "cellules-ie 'mateial'in suoh 4a mannerlthatmanyoffthef-dim- 1ciilties enumerated Vabove fare avoided; 11n "iaccordanfce with preferre'd embodiments `flo'f'the f in- `vl'enti'on,this is accomplished bylolitainngia'fniore uniform and completo coating or impregnation o"f 1the 'cellulosic 'libera-With the ir'np-'egnatin'g agent prior to the felting orfforihingfstep. A 'second important `object i is ft'o provide 'a preoess l'for the incorporation 'f of -a -vwide 'fiariety'iof llin- \pregiiating=agents into or-uponfforoos "eniilosi'c inmaterial'in such 2a nrianner that these added "materiais'oo not seriouslyiriteferefwithftneorrna'l method of 'production'f j'p'ap'er pulp sh ets, `'pulp v"preforms ami-r theiike on lstandardjpaper- Vnialirig equipment, 'even 'when ilarge quantities of.' impregnating materials "are yused. A finftiie'r object is to eliniiiia'tej'rnany' of the ldileultie's ordinarily" eneoui'itered in the' ceag'ulationjoff inous -dispersions by lin'organi'c y precipitating agents suon as .aluminoluirig'dilnolties arising throughnon-uniform coverage of thelpiilpiiibers, formationoilstilry aggregates ofthepreopit ted material, and extremely slow drain'alg'l of Water :from agglomerated resin-fiber masses on the sheet-formingwir'e orscreen.,` v

Further i objects of the invention involve *the formation, on standard paper-inakingi "or pulpforming r performing e'quipi'nerit,v of "easily new combinations-of iibers, .or "if'iber's an with certain special resinorus impregnating that have not heretofore been incorporated suc'- cessfully by slush stock treatment. Thus, for example, certain special thermosetting resins or condensates such as urea-formaldehyde resins, phenol-formaldehyde resins, alkyd resins and the like may be incorporated into paper stock in the quantities necessary for premolding and molding processes. v

Similarly, a wide variety of organic binders, sizing agents, oils, waxes, pitches, gums and natural resins may be incorporated into fibrous cellulosic materials. Various combinations of any two or more of these materials may likewise be incorporated if desired. By applying the principles of this invention, resin-impregnated paper or paper board having superior properties can be prepared, as well as new types of products made from the treated paper of pulp by such conventional operations as laminating, molding, pressing, calendering, extruding and the like. Instead of forming the treated pulps or fibers, they can be shredded, chopped or ground to produce new types of insulating agents, molding powders, fillers for standard molding or casting resins, and the like.

The present invention is based on the discovery of an unusual type of flocculation and deposition that is brought about by the action of cationic urea-formaldehyde resins in an aqueous system containing fibrous cellulosic material of the type of paper pulp suspended therein together with an aqueous dispersion of waterinsoluble coating or impregnating agents.V It has been found that in such a system the cationic urea-formaldehyde resin causes a controlled flocculation such that particles of the impregnating agent are uniformly coated upon or impregnated into the cellulose fibers. When dispersed or deflocculated water-insoluble impregnating or coating agents are applied in this manner, the cellulosic fibers retain their property of felting or forming into shaped or sheeted articles despite the presence of large Aquantities of the impregnating agent, which in some cases may even be greater than the weight of the cellulosic fibers themselves.y Moreover, when the proper quantities of cationic urea-formaldehyde resin are applied in the manner hereinafter described a high degree of retention of the flocculated material by the cellulosic fibers is obtained, and losses of organic material in the white Water system are largerly avoided.

The` process of the invention therefore comprises as an essential featurey the occulation of an aqueous dispersion of an impregnating agent in the presence of fibrous cellulosic material suspended inthe aqueous medium by the action of a cationic urea-formaldehyde resin. The distinctive type of ilocculation that is obtained when an aqueous solution of this type of resin is added to an aqueous dispersion such, for example, as an emulsion-polymerized polystyrene dispersion will be described and illustrated hereinafter in greater detail.

The invention in its broader aspects includes any process wherein this flocculating action is used for the dispersion or incorporation of an impregnating agent into fibrous cellulosic material.

In addition to the foregoing. one of the most importantfeatures of the invention is the discovery that the distinctive fiocculating action of the cationic urea-formaldehyde resin continues, and is in many instances actually enhanced, after the cationic resin has been absorbed on the brous cellulosic material. The importance, of this discovery resides inthe fact that the cationic resin, being distributed over and through the cellulosic fibers, causes a uniform dispersion and retention of the impregnating agent on the fibers after it has been flocculated. Large quantities of -any desired impregnating agent may therefore be deposited on brous cellulosic materials such as paper stock while retaining the felting properties of the fiber, so that after impregnation they can still be felted together and formed into sheeted or molded products by conventional wet-molding or papermaking procedures.

Although the invention is not dependent on any particular theory of operation, the following is offered as the most satisfactory explanation of the unusual type of occulation and retention that is obtained. As is noted above, definite quantities of the cationic urea-formaldehyde resin are adsorbed upon and retained by the cellulosic bers when the cationic resin solution is added to an aqueous suspension thereof. As a result of this treatment, the ber-resin entity becomes positively charged, as contrasted with the negative charge usually associated with cellulose fibers. The resulting positively charged,

vresin-treated fibers in aqueous suspension exert an appreciable flocculating action on emulsions or dispersions of water-insoluble organic materials, and this is particularly evident when the emulsified or dispersed impregnating material carries a negative charge as when an anionic dispersing agent is employed in its preparation. The result is that after addition of the emulsion or dispersion of the impregnating agent to the aqueous suspension of resin-treated cellulosic pulp, the dispersed particles are occulated on the positively charged iibers forming a coating upon and around the fibers and permitting the formation of a mat of the coated fibers on a screen or paper machine wire, with substantial retention of both the fibers and the coagulated particles of the non-fibrous dispersion.

The cationic urea-formaldehyde resins which are employed in the process of our invention are prepared sby condensing a urea-formaldehyde reaction product under acid conditions, and preferably at pI-I values below 4.0-4.5, in the presence of a cationic nitrogen-containing organic compound =which is capable of condensing with the resin. The preferred cationic organic nitrogen compounds which are capable of condensing with diirnethylolurea or other urea-formaldehyde reaction products are water-soluble rpolyfunctional organic nitrogen bases; i. e., compounds having the ability to copolymerize with lurea-formaldehyde under acid conditions. Typical examples of such polyfunctional organic bases are the alkylene polyamines of the formula:

H2N(CnH2n.HN) xH in which :c is one or more, such as ethylenediamine, 1,3-propylenediamine diethylenetriamine,

triethylenetetramine, tetraethylenepentamine, the corresponding polypropylenepolyamines and `polybutylenepolyamines, also guanidines, biguanproducts,- obtainedunder slightly alkaline conditions. by .condensing ureazor` thiourea. .with forme therefore prepared by first reactingI ureal With' amethylene-yielding substance suc-h aslformaldeh'yde, paraforrnaldehyde,v orhexameth'ylenetetramine-in known vmannerfto formL-ay primaryurea-formaldehyde condensation l product which is usually designated -by resin chemists `as. dernethylolurea. product is'preferablyformed under neutral orslightly alkaline` conditions, the latter being obtained-by theaddition of a smal-l vquantity -of basic materialfsuch' as sodium; hydroxide oratriethanolamine. A suitable quantity ofthe poly-- functional orga1iic-b`aseI is-then added-'as such or` after it has first beenreacted'- with formaldehyde'andthe resinsolution'is-'a-cidied-by the addition-o1 Vhydrochloric acid; nitric acidy or other strongly acidic material to'reducethe-pH` tothe polymerizing range,fwhich is about 1-4 and preferafbly Y1-2.- The resin-syrupis then further reacted o-r polymerized; preferably rat elevated Vtemperatureson the order-of 70-90' C., inI order'to bring about Ya polymerization or copolymerization' of the urea-formaldehyde yand* organic ybase andthereby-produce va cationic resin'.`

'The relative proportions of polyalkylene poly-` arnine and primary `urea-formaldehyde condensation product may be varied over a wid-e range. This is an important advantage .of the invention, since it permits an adjustment ofthe degree of cationic properties .of the resin for lemulsions of Widely divergent characteristics including, vfor example, those containing anionic or non-ionic emulsifying agents.l Thus for somepllrposes -it' maybe most desirable to employ a resin preparedv from %V fbyeweight of. a polyalkylene polyamine andl 90% of urea-formaldehyde condensation` product, While for other purposes a cationic resin containing considerably more of the pflyalkylenel polyamine may give better results. Cationic resins prepared from as much as 80 %j by Weight of a polyalkylene polyamine such'as tetramethylenepentamine and lby Weight of .the primary u re'aformaldehyde condensation product may be used in cases Where rapid curingof theresin is not important.

Thepolyrnerized resinsyrup is preferably neutralized to a p I-I on the order of about .6 7 in order to obtain `a product whichV is stable on storage.V Resin syrups prepared. by thismethodv are both=waterso1ub1e and lwater dilutable, and also vcan be evaporated to dryness and ,redissolved in water Without substantial reductionin their Water solubility.

The process of the invention may thus be used to .app-ly any'water-insclwble coating or impregnatingt agent in amounts varying from a few. lpercentgup to more thanthe weight of the fibrousv -cellulosic material'. By coating or impregnating agen We mean, of course. a material. which will coat or impregnato the cellulosic lbersand irnprove their; value. for their intended Zuse. The great majority of coating and impregnating Inaterials' used *,inpracticing the. invention-are organic-amorphous or micro-crystalline materials This primary reaction 6. of. :the type, of. waxes, gums, resins. .and the '.vlikei The` following .types of materials of this. class are illustrative. of thewide variety .of impregQ hating agents Which'rnay be applied;

Wares Petrolatumv Microcrystallinev or: amor- .fphous petroleumwax Parailn Crude scale wax Carnauba .Wax

Montan 'was Chlorinated waxes.v

Bituminous Asphalt f Bitumens Tars andtpitches Resins' Wood rosin Hydrogenated rosin.. Gumrosin Limedrosin Heat-treated rosin Disproportionated rosin Acid-treated or poly-f merized rosin vSulfur-treatedlrosin.

Elastomers Natural latices Synthetic latices Butadiene polymers Copolyiners of buta- Isoprene polymers diene, isoprene, etc. Neoprene polymersv With acrylonitrile Resins-thermosettmg Resins-thermoplastic Polyvinyl compounds Polystyrene Polyacrylates Polymethacrylates Poylvinyl esters such as vinyl chloridesand vinyl acetate polymers and copolymers of the two Polyvinyl acetal Polyvinyl alcohols Copolymers of styrene .with vinyl chloride,gacrylic acid esters, acrylonitrile, etc.

Thermopla'stic phenol-formaldehyde resins, including phenol-aceta'ldehyde .and phenol-furfural resins and corresponding resins obtained from cresols and other alkyl phenols Oil-modified phenol-formaldehyde resins E'sters of rosinvvith polyhydric alcohols suchas glycerine, pentaerythritol, dipentaerythritol, polyallyl alcohols, etc.

Polyindene resins C'oumaronc resins Vinylacetylene resins Vinso1" resin; i. e. residue from purified wood rosin Halogenated vinylacetylene resins Acetyl. gums Any of the above materials, either singly. or in admixture, may be applied to fibrous celllosic materials with the aid of cationic urea-formaldehyde resins by the process of the present invention. The impregnating agent is added to the aqueous stock suspension containing the cellulosic lbers as a dispersion in Water or aqueous liquid. Depending on the type of impregnating agent, the dispersions may require no added emulsifying or dispersing agents whatsoever, as in the case of natural latices. However, in many cases dispersions of finer particle size and :better impregnating properties are obtained with the ald of dispersing agents, and many types of dispersing agents may be used. In general any anionic or non-ionic dispersing agent may be employed in emulsifying or suspending the impregnating agents in Water or other aqueous liquids, and in certain cases the cationi-c emulsifying agents may also :be used. Typical anionic, emulsifying agents which have been employed with success are the soaps of aliphatic and cycloaliphatic acids such as potassium oleate, potassium naphthenate and the like, amine salts such as triethanolamine oleate; sulfated aliphatic compounds such as sodium lauryl sulfate and the sulfates of higher secondary alcohols and sulfonated castor oil; sulfonated products such as sodium keryl benzene sulfonate, sodium isopropyl naphthalene sulfonate, esters of sulfo-carboxylic acids such as esters of sodium sulfo-acetate, dialkyl sulfosuccinates, disodium monoalkyl sulfosucclnates; amides of sulfo-carboxylic acids such as lsodium sulfosuccnamates and the like, sulfonated lignin, etc.

Ammonium or other water-soluble or waterdlspersible salts of alkyd resins of high acid number may also be employed, such as the products obtained by adding sodium hydroxide to condensation products of maleic acid and -glycerine, modified phthalic anhydride-glycerinefatty acid condensation products of high acid number, polyhydric alcohol esters of terpenemaleic acid condensation products and the like. In general, therefore, any suitable :wetting or emulsifying agent may be used in practicing the invention.

Any fibrous cellulosic material capable of ad-y sorbing cationic urea-formaldehyde resin from an aqueous solution thereof may be coated or impregnated by the process of the invention. A wide variety of fibrous cellulosic material used in the preparation of paper, board, molded resin fillers and the like may be used, such as kraft pulp. rag pulp, soda, sulfate, ground-Wood, `sulflte pulp and alpha pulp. Similarly, other forms of fibrous cellulose such as cotton lnters, and the like may ibe Iemployed. These materials may be used alone or in adrnixture with fibers from other sources, s-uch as jute, hemp, sisal, strings, chopped canvas, asbestos fibers, glass fibers, and other material, either cellulosic or non-cellulosic, that may improve the impact resistance, mechanical strength or other properties of the formed or molded impregnated material. Typical products that may be improved by the process of the invention are -waterproof or moisturevaporproof paper, paper or board containers or cartons for milk, butter, foods, etc., resin-impregnated laminating paper, abrasives composed of resin-impregnated paper coated with abrasive particles, molded articles, premolded articles, electrical insulators, filter paper, heat-insulating paper, or loose masses of unfelted and unmolded impregnated cellulose stock used for air filters, dust filters, heat insulation and the like.

The particular procedure whereby the impregnating agent is occulated and coated on the brous cellulosic material may vary somewhat with different impregnating agents, but usually follows the same general plan. The cellulosic material is preferably rst suspended in water and may be beaten for shorter or longer periods of time, after which the stock may be brushed out in a Jordan engine or other refining machine if desired. Any desired ratio of cellulosic material to water may be maintained but We prefer to operate at a stock consistency of about 0.5% to 6%. The cationic urea-formaldehyde resin is then added, preferably in the form of an aqueous solution of about 5%-l5% resin solids, after which the stock suspension is preferably allowed to stand for anywhere from 15 minutes up to 3-4 hours or longer. This period of aging is not a lnecessary step, since the adsorption of cationic resin by the paper pulp is quite rapid, but the subsequent behavior of the impregnated stock on a paper-making machine is much better when the addition of the impregnating agent is delayed for this period of time. The pH of the stock during the adsorption of the cationic urea-formaldehyde resin and prior to addition of the impregnating agent should preferably be within the range of from about 1 to about 6 since the resin retention is not as good at higher or lower values.

After pretreatment of cellulosic fibers with the cationic urea-formaldehyde resin, the impregnating agent is introduced in the form of an aqueous suspension, preferably of relatively ne particle size. The flocculating action of the cationic urea-formaldehyde-polyamine resin is not dependent on the particle size of the added impregnating agent, but a much more uniform coating of the cellulose fibers and better performance on the paper-making machine is obtained when a dispersion of 'lne particle size is used. Aqueous dispersions having an average particle size of l-Z microns or less have given excellent results in practice, and therefore we recommend the addition of the impregnating agent in the form of an aqueous dispersion having at most this particle size. The flocculation' of the impregnating agent and its adsorption by the cationic resin-treated cellulose fiber is fairly rapid, and the standing time of the mixture after the impregnating' agent has been added makes very little difference in the resin retention. The stock can therefore be formed immediately after the addition of the impregnating agent or after a considerable period of time, as desired. However,l a more uniform impregnation of the stock is sometimes obtained when the impregnating dispersion is added slowlir to the resin-treated stock instead of adding it all at once. In continuous operation, where the resin dispersion is added continuously to a stream of the treated stock, this effect can be obtained by introducing the resin dispersion simultaneously at several points in the stock-treating system. Alsovthe point of addition can be selected so that the time of contact available for occulation before sheet formation is adjusted to give maximum iiocculation.

The optimum quantity of the urea-formaldehyde resin that should be used to obtain the best retention of a dispersed or emulsied resin, wax, or other impregnating agent may vary with the nature and particle size of the dispersion, the nature of the cationic resin, the time of contact between the pulp` fibers and the .cationic resin solution, the pH of the stock and other factors. Also. because of the properties of vthe dispersed `accuses material added `and thev requirements of the finished-sheet or-article to be made, it maybe desirableto modify the proportion of urea-formaldehyde resin in order to obtain increased properties thereof 'in the finished product. In generaL'the proper amount of urea-formladehydeA resin. required mayvary from small amounts on the order ofl based on the Weight of the paper stock, up .to :about 15 or more. When using relatively large 4quantities of-impregnating agent, on the order of 50%100% or more of the Weightof the cellulosicbers, the optimum quantity of cationic resin is within the range of about 1 %-1.0%., based on the'weight of resin solids in the' impregnating agent. With'smallerquan'tities of impregnating agent such as 5%50% on the Weight of the cellulose," larger quantities of the cationic resin should be used. ,'Largerquantities of the modied ureaformaldehyde resin up to 100% or more `'on the weight of the impregnating agent may be fadded to modify the properties'of the -nished product if desired, but in such cases there 'is 'denitefalling olf inthe `retention and also an increase in the drainage time of the stock. It is usually desirable to'run'trials with t-he specific dispersion of impregnating agent to be added, using the desired operating conditions, before deciding finally upon the exact proportions of cationic urea-formaldehyde resin to use.

The principles of the invention may be applied in a wide variety of fields of paper making, molding, laminating, extruding, preforming and the like and in general Wherever a fibrous` cellulosic material intimately associatedwith thermoplastic, thermosetting, waxy, bituminous or other type of bonding,impregnating or coating material is .desired.

The' invention Will be further illustrated bythe following specific examples, whichl show preferred embodiments thereof. It should-be understood, however, that the invention in its-broader aspects is-not limited to these examples, but that other modifications and variations in materials,:quan tities and procedures may be resorted towithin the scope of the appended claims. y

Example 1 'Aslution of 271.2 grams of 37% formaldehyde and80 grams of urea Was adjusted to a pH of SLB-f8.8 with triethanolamine, and the mixture wasthereafter heated at 70 C. for 15v minutes. 8 grams `.of tetraethylenepentamine Was .then added to the mixture, together with l2 grams of water, and after slight cooling, 12=grams of commercial hydrochloric acid diluted with an equal amount of Water wasv added to the mixture. The temperature of the mixture was brought to 70 C..and maintained at this point for 1 hour. Thereafter the cooled viscous syrupy was neutralized with sodium hydroxide, under which conditions the resin remained stable.

Bleached kraft pulp, at a Green freeness of 475 andapproximately 1.5% consistency lwas treated with various amounts of the above resin, as set forth in the table below, rand allowed-to stand for several hours at a pH of 4.0-5.0. The slurry was then adjusted to a pH of about 6.5 with dilute sodium hydroxide and a polystyrene emulsion, equivalent to 100% on polystyrene solids, of the dry fiber weight was added to the slurry Which'was then stirred for'15-'30 minutes. Thereafter, the slurry Was diluted to 1% liber consistency. Handsheets were'then made on a Williamsfreeness tester employing approximately 200 cc. of the fiber-resin suspension for each 10 sheet. The sheetswere dried to constant weight at about C. The. polystyrene used inthis and the other illustrative examples Was prepared as follows: 1.2 parts by Weight of sodium lauryl sulfate were dissolved in 58.8 parts of Water heatedv to l94 C. and 0.05 part of 40% hydrogen peroxide were added. 40 parts of styrene were then introduced uniformly over 1.5 hours,'with agitation sufficient to cause emulsication thereof. The exothermic polymerization reaction proceeded smoothly vand Was complete after .3.5 hours. Steam was blown through the batchl to remove unpolymerized material and the dispersion was adjusted to 25% solids.

Additional cationic resins Were prepared was follows Example 2 33.75 grams of urea and 142 grams of137% formaldehyde solution Were reacted under slightly alkaline conditions for 15 minutes at 70 C. Following this reaction period, l23.75 gramsfof tetraethylenepentamine and sufcient concentrated hydrochloric .acid Were added togivea pH of about 13 and the condensation .was continued byheating at 70 C. for an additional 1/2 hour. i

Example 3 Afresin syrup wasl prepared in the same Way as in Example 2 employing 11.25. grams of urea, 131 grams of 37% 'formaldehyde solution and 47 grams of tetraethylenepentamine.

Ervample4 A solution of 18.9 grams of -tetraethylenepentamine in 40 m1. 'of Water was partially neutralized bythe sloW'- addition of 8.3 ml. of concentrated hydrochloric acid. The mixture was then cooled and Vto'the amine'solution was added slowlya cooled solution of 6.6 grams of acetaldehyde and 24.3 ml. off37% "formaldehyde, VA Viscousresin formed as a result of the strongly exothermic reaction. It was dilutedwith Water to make l"a stable solution of 5% solidscontent.

Example 5 vExample `6 60 grams of urea were dissolved in 202 grams of 37% formaldehydesolution and the pH was adjusted to 8.5 by the addition of sodium hydroxide solution. The mixture was heated at. 70 C'. for 15 minutes and thereafter 1 ml. of concentrated hydrochloric acid Was added, followed by the addition of 24 grams of ethanoldiamine added as the hydrochloride. The mixture was heated at 70 C'. for 1 hour and the reaction mixture was thereafter neutralizedk With sodium hydroxide solution.

The above described :resins of Examplesf2 -6 were employed as precipitants for'polystyrene resin -on 'bleached kraft pulp according to *the What we claim is:

v 1. In a method of making a formed cellulosic product by the steps of preparing an aqueous suspension of fibrous cellulosic material, impregnating the cellulosic material with a waterinsoluble hydrophobic organic impregnating agent and forming the impregnated cellulosic material into a felted product, the improvement which consists in first adding a partially polymerized hydrophilic cationic urea-formaldehydepolyfunctional organic nitrogen base resin to the aqueous fibrous suspension, said cationic resin being formed by the condensation of a ureaformaldehyde reaction product with a watersoluble polyfunctional organic nitrogen base under acid conditions, then adding an aqueous dispersion of the organic impregnating agent in deflocculated condition and thereby immediately occulating the impregnating agent in the cellulosic fibrous suspension by the action of the cationic urea-formaldehyde-polyfunctional organic nitrogen base resin, and thereby depositing a substantial proportion of the impregnating agent uniformlyon the fibers.

2. A method of impregnating brous cellulosic material with an organic impregnating agent while preserving the freeness and felting properties thereof which consists in preparing a water suspension of the fibrous cellulosic material at 0.5%-6% consistency, adding to'said suspension a cationic urea-formaldehyde-polyfunctional organic nitrogen base resin in amounts of 1-l5% of the Weight of the fibrous cellulosic material, said cationic resin being formed by the condensation of a urea-formaldehyde reaction product with a Water-soluble polyfunctional organic nitrogen base under acid conditions, aging the suspension in non-alkaline condition for at least 30 minutes, then adding an aqueous dispersion of the organic impregnating agent in deocculated condition, thereby immediately fiocculating'the impregnating agent in the cellulosic fibrous suspension by the action of the cationic urea-formaldehyde-polyfunctional organic nitrogen base resin, and thereby depositing a substantial proportion of the impregnating agent uniformly on the fibers.

3. A method of impregnating brous cellulosic material with 50-100% of its weight of an organic impregnating agent while preserving the freeness and felting properties thereof which -consists in preparing a water suspension of the fibrous cellulosic material at 0.5-6% consistency,

adding to said suspension a partially polymerized hydrophilic cationic urea-formaldehyde-polyfunctional organic nitrogen base resin in amounts of about 1%-15% of the Weight of the brous cellulosic material, said cationic resin being formed by the condensation of a ureaformaldehyde reaction product with a watersoluble polyfunctional organic nitrogen base under acid conditions, aging the suspension in a non-alkaline condition for at least 30 minutes, then adding the requisite quantities of an aqueous dispersion of the organic impregnating agent in deflocculated condition, thereby immediately occulating the impregnating agent in the cellulosic fibrous suspension by the action of the cationic urea-formaldehyde-polyfunctional organic nitrogen base resin, and thereby depositing 50-100% by weight of thev impregnating agent on said bers.

4. A method according to claim 1 in which the hydrophobic organic impregnating agent is a polystyrene resin.

JOHN H. DANIEL, JR.

LUCIUS H. vVILSON. l RANDALL HASTINGS. CHESTER G. LANDES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,799,216 De Cew Apr. 7, 1931 1,992,589 Tucker Feb. 26, 1935 2,027,090 Carter Jan. 7, 1936 2,197,383 Outterson Apr. 16, 1940 2,255,834 Taylor Sept. 16, 1941 2,277,788 Shipp Mar. 31, 1942 2,291,079 Holerbert July 28, 1942 2,291,080 Hoiierbert July 28, 1942 2,325,302 Britt July 27, 1943 2,325,987 Swain et a1. Aug. 3, 1943 2,338,602 Schur Jan. 4, 1944 2,338,839 Coss Jan. 11, 1944 2,343,095 Smith Feb. 29, 1944 2,375,244 Pretzel May 8, 1945 2,394,009 Pollard Feb. 5, 1946 2,401,027 Tausch May 28, 1946 2,407,376 Maxwell Sept. 10', 1946 2,416,447 Laughlin et al Feb. 25, 1947 2,474,801 Owen June 28, 1949 2,487,899 Sherman Nov. 15, 1949 2,554,475 Suen May 22, 1951 FOREIGN PATENTS Number Country Date 555,148 Great Britain Aug. 6, 1943 OTHER REFERENCES Paper Trade Journal, August 9, 1945, pages 37, 39 and 46.

Paper Trade Journal, August 14, 1947, pages 57 to 60. p

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Manufacture of Pulp and Paper, 3rd ed., vol. IV, sec. 5, page 18 (1938), McGraw-Hill, New York. 

1. IN A METHOD OF MAKING A FORMED CELLULOSIC PRODUCT BY THE STEPS OF PREPARING AN AQUEOUS SUSPENSION OF FIBROUS CELLULOSIC MATERIAL, IMPREGNATING THE CELLULOSIC MATERIAL WITH A WATERINSOLUBLE HYDROPHOBIC ORGANIC IMPREGNATING AGENT AND FORMING THE IMPREGNATED CELLULOSIC MATERIAL INTO A FELTED PRODUCT, THE IMPROVEMENT WHICH CONSISTS IN FIRST ADDING A PARTIALLY POLYMERIZED HYDROPHILIC CATIONIC UREA-FORMALDEHYDEPOLYFUNCTIONAL ORGANIC NITROGEN BASE RESIN TO THE AQUEOUS FIBROUS SUSPENSION, SAID CATIONIC RESIN BEING FORMED BY THE CONDENSATION OF A UREAFORMALDEHYDE REACTION PRODUCT WITH A WATERSOLUBLE POLYFUNCTIONAL ORGANIC NITROGEN BASE UNDER ACID CONDITIONS, THEN ADDING AN AQUEOUS DISPERSION OF THE ORGANIC IMPREGNATING AGENT IN DEFLOCCULATED CONDITION AND THEREBY IMMEDIATELY FLOCCULATING THE IMPREGNATING AGENT IN THE CELLULOSIC FIBROUS SUSPENSION BY THE ACTION OF THE CATIONIC UREA-FORMALDEHYDE-POLYFUNCTIONAL ORGANIC NITROGEN BASE RESIN, AND THEREBY DEPOSITING A SUBSTANTIAL PROPORTION OF THE IMPREGNATING AGENT UNIFORMLY ON THE FIBERS. 